This invention relates in general to antifriction bearings and more particularly to a cage capable of enabling a tapered roller bearing to operate at high speeds and also to a bearing assembly including such a cage.
In the typical tapered roller bearing the tapered rollers roll between an inner race, known as a cone, an outer race, known as a cup. Actually, the rollers contact the cup and cone along tapered raceways on those components and if each raceway is extended to an apex, the apexes of the two raceways would lie at a common point along the axis of rotation for the bearing. This configuration produces pure rolling contact between the rollers and the cup and cone raceways. It also causes transmitted radial loads to resolve into axial components at the rollers, these axial components being directed such that the rollers are urged toward the large ends of the raceways. To prevent the rollers from being expelled from the annular space between the cup and cone, the cone is usually provided with an outwardly directed rib that is capable of resisting the axial component exerted on the rollers. Thus, during operation of the bearing, the large diameter end faces of the rollers bear against, roll, and to a measure, slide along the cone thrust rib.
Unless a film of lubricant is maintained between the cone thrust rib and the roller end faces, the bearing will overheat and sustain damage. During low speed operation the tapered rollers tend to pump any lubricant that is within the bearing toward the thrust rib, and as a consequence the thrust rib usually receives an adequate supply of lubrication. However, during high speed operation, particularly with a rotating cone, the centrifugal forces imparted to the lubricant tend to direct it away from the thrust rib, and as a result the thrust rib and roller end faces become starved for lubrication. For this reason, conventional tapered roller bearings are usually not suited for high speed operation.
However, tapered roller bearings have many characteristics that are not found in angular contact ball bearings and other types of bearings that are currently used in high speed applications. For example, tapered roller bearings, by reason of the line contact between the raceways and the tapered rollers, will carry radial loads of extremely large magnitude. Also, they are capable of carrying thrust loading as well as radial loading, and when two single row bearings are mounted in opposition, the two bearings can be set up against each other to achieve the desired amount of end play or preload in the mounting. Furthermore, such a mounting is extremely stable.